A single defect in one piece of code can cause different apparent problems to different users. It is also possible that a single reported problem may be traceable of multiple different pieces of code that are similarly faulty.

Therefore:

Several reported failures that arise out of the same fault should be tracked together. Consider splitting a single bug with multiple causes into a bug for each fault, and relate them as above.

However:

The bug tracking software must support the ability to associate bugs as duplicates of and dependent on other bugs. Splitting a single bug or otherwise tracking related bugs without good support from the tool requires too much manual overhead.